Walleye

Electro-shocking for walleye broodstock.	Hand stripping eggs from a female walleye.
Eyed eggs, 7 days after fertilization	Walleye fry, 3 days old
Fertilizing ponds with alfalfa pellets	Stocking walleye fry in a hatchery pond
Checking on growth and weight counts. These fish are fed a high protein dry diet.	Moving walleye to new tanks. Weight counts are taken every two weeks to monitor growth and tank density. Fish are divided to other tanks to prevent overcrowding.
Stocking walleye in the fall. Approximately 20,000 - 30,000 walleye are distributed mid-September when they average 6 - 8 inches in length.

Broodstock walleye are not kept at hatcheries year-round, each year when spawning time occurs, broodstock walleye must be collected by electro- shocking. Walleye are collected from the Black River in Southeast Missouri, Stockton Reservoir, and the Harry S. Truman Dam tail waters when the water temperature approaches 48 degrees F - 50 degrees F. Broodstock are transported to a hatchery and held in tanks until spawned.

Upon arrival at the hatchery, eggs are collected from females that are releasing (ovulating) their eggs. The females are hand stripped to collect their eggs. These eggs are fertilized with freshly collected semen. However, when brought to the hatchery, most females are not ready to spawn and require a hormone injection to induce ovulation. A small sample of eggs is collected from each female to determine the stage of egg development. The samples are examined microscopically and the amount of time until ovulation is determined. Semen from male walleye is collected, preserved, and stored at 38 degrees F - 45 degrees F.At the time of ovulation the eggs are collected and fertilized with preserved semen. On average 175,000 - 200,000 eggs are collected from one female. A clay treatment is mixed with the eggs to prevent them from sticking together.

The eggs are then placed in specially designed incubation/hatching jars. Water is piped down the center of these jars then flows up from the bottom, which, rolls the eggs and keeps them in suspension. Dead eggs are removed daily. Therapeutic treatments are administered as needed to control fungus which will kill the eggs if left untreated. At 60 degrees F the eggs will hatch after 7 - 10 days of incubation. As the eggs hatch, the fry swim up and out of the hatching jars into large circular holding tanks where they are held until they are stocked into lakes and hatchery ponds.

Ponds designated for walleye production are filled the previous fall. Two weeks prior to stocking, ponds are fertilized with organic fertilizers such as dehydrated alfalfa meal or pellets, soybean meal, dehydrated cow manure or fresh turkey manure. Fertilization increases the quantity and quality of food organisms such as zooplankton. Fertilizers are applied at 100 - 250 pounds per acre per week. During the rearing period zooplankton populations are monitored weekly.

Approximately 3 to 5 days after hatching, fry are stocked into the hatchery ponds. Stocking rates range from 120,000 to 200,000 fry/acre. Dissolved oxygen and pond temperatures are monitored daily. To check on survival, a flashlight held close to the pond surface at night will attract plankton and walleye. This helps to check on survival and growth of the walleye.

Ponds are drained when the walleye (fingerlings) obtain a size of 1.5 - 2.0 inches in length. Approximately 300,000 - 500,000 walleye fingerling are harvested and stocked in Missouri Lakes each year. Some years a portion of the fingerling are put in tanks in the hatchery building to be grown to a larger size before release.

These fish are fed a high protein dry diet. The feed is dispensed from automatic feeders every five minutes 24 hours a day. After six weeks, feeders are adjusted to feed every fifteen minutes. This rate continues until fish are harvested. To minimize cannibalism, walleye are graded to separate fish by size.